Choosing 13.8V to 3.3V Switch Mode Voltage Regulator

I'm designing a circuit with some IC's that is supposed to have a 3.3V voltage supply. My voltage source is a 13.8V battery pack. I'm looking for a high efficiency voltage regulator to supply the circuit, but I'm inexperienced in this area and would like some help finding the best solution. The circuit will have a max current of about 300-400 mA.

The efficiency of the regulator is extremely important, because the batteries will have to last as long as possible before recharging is necessary.

RWM over 13 years ago

For best efficiency you need IC which uses synchronous rectification. For example LM3103MH/NOPBLM3103MH/NOPB
http://www.ti.com/product/lm3103
Efficiency about 93%. You can use Webench (available on the page mentioned above) to design and simulate your regulator circuit.
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Former Member over 13 years ago in reply to RWM

Thank you! I will look into it.

The fact that the current in the circuit will normally be about 1-3 mA (there are components that will be switched off when not in use) may be another thing to consider when choosing a voltage regulator. I don't have much room for a heatsink, so that's another reason to get a highly efficient buck converter.
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RWM over 13 years ago in reply to Former Member

If the circuit needs normally 1-3 mA, you should use regulator with pulse skipping mode at light loads (or Eco mode etc.) because standard regulators have bad efficiency at light loads. For example you can use http://www.ti.com/product/tlv62150 (efficiency about 80% at 1mA load and about 90% at 400 mA load).
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Former Member over 13 years ago in reply to RWM

Thank you!

Do you have examples of other usable regulators? That perticular one seems to be hard for me to get a hold of (can't find it in the electronic shops). I've been searching around the web for replacements, but I'm overwhelmed by all the information and parameters that need to be considered.
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RWM over 13 years ago in reply to Former Member

There is a lot of step-down regulators, but you need to find information on low current efficiency, so search datasheets. Perhaps it is posssible to obtain a sample of above mentioned ICs from TI. Other types:
http://uk.farnell.com/texas-instruments/tps54528dda/buck-sync-adj-5a-8so/dp/2064230?Ntt=tps54528
Efficiency about 90% at 400mA but about 50% at 3mA.
http://www.ti.com/product/tps54428
http://uk.farnell.com/texas-instruments/tps54428dda/buck-sync-adj-4a-8sop/dp/2078519?Ntt=tps54428
Efficiency about 90% at 400mA but about 45% at 3mA.
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RWM over 13 years ago in reply to Former Member

You can use also LT3695:
http://www.linear.com/product/LT3695
http://cds.linear.com/docs/Datasheet/3695fa.pdf
http://uk.farnell.com/linear-technology/lt3695emse-3-3-pbf/ic-step-down-regulator-msop-16/dp/1783337
Efficiency about 84% at 400mA and 62% at 3mA.
or LT3435
http://www.linear.com/product/LT3435
http://cds.linear.com/docs/Datasheet/3435fa.pdf
http://uk.farnell.com/linear-technology/lt3435efe-pbf/ic-switching-reg-adj-smd-tssop16/dp/1273811?Ntt=lt3435
Efficiency about 85% at 400mA and 72% at 3mA.
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